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When remanufacturing saves energy

If you are interested in using remanufactured components, you might do so for reasons other than that of energy efficiency. It turns out that when viewed from the standpoint of energy use, remanufactured goods are a mixed bag.

So say researchers from the Mass. Institute of Technology in a recent issue of the journal Environmental Science and Technology. MIT mechanical engineering professor Timothy Gutowski and a team of 25 researchers examined remanufactured goods that included furniture, clothing, computers, electric motors, tires, appliances, engines, and toner cartridges. What all these products have in common, says Gutowski, is that they consume far more energy during their operating life than what goes into their manufacture. The rub is that often “new technology shows up that is so much more efficient, from an energy point of view, that you should get rid of the old device” rather than having it fixed or buying a remanufactured version, Gutowski claims.

For example, many new appliances — such as refrigerators and washing machines — feature efficiency improved over older models to such a degree that, in terms of energy use, a new model is almost always the better choice, he says.

Even retreaded tires sacrifice energy efficiency. It does indeed take less energy to make a retread, but their rolling resistance can be higher. So energy saved during manufacture can be eaten up by the extra gas needed to push the vehicle.

Similarly, remanufactured electric motors with rewound stators are typically 0.5 to 1% less efficient than a new motor. “There is still a cost advantage” to the remanufactured motors, Gutowski says, “but from an energy point of view, it’s the opposite.”

Of course, there can be other reasons besides those of energy efficiency to remanufacture parts and products. And there are typically no efficiency tradeoffs for remade products -- such as furniture -- that consume little energy. “We’re not saying you shouldn’t do it,” Gutowski says. Rather, it’s worth understanding the decision to remanufacture in its entirety.

MIT put out a release on Gutowski's paper: http://web.mit.edu/newsoffice/2011/remanufacturing-0516.html

Environmental Science and Technology link: http://pubs.acs.org/doi/full/10.1021/es102598b

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